Shell script to define the post_max_size and the upload_max_filesize values in the php.ini file.

configPhpMaxSize.sh

#!/bin/bash

if [ $# -ne 1 ]; then
    echo "One parameter expected:"
    echo "- the new size limit (in Mb)"
    exit 1
fi

SIZE_IN_MB=$1
if [[ ! $SIZE_IN_MB =~ ^[0-9]+$ || $SIZE_IN_MB -eq 0 ]]; then
    echo "$SIZE_IN_MB is not a positive integer"
    exit 1
fi

setValue()
{
    PHP_PARAM=$1
    sed -ri 's/^('$PHP_PARAM' = ).*$/\1'$SIZE_IN_MB'M/1' /etc/php/7.2/apache2/php.ini
    if [ $? -ne 0 ]; then
        echo "Error on setting the $PHP_PARAM value"
        exit 1
    fi
    echo "Parameter $PHP_PARAM set to $SIZE_IN_MB"
}

setValue "post_max_size"
setValue "upload_max_filesize"
exit 0